Acquisitions, Goodwill And Other Intangible Assets (Schedule Of Other Intangible Assets) (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Acquired Intangible Assets
Accumulated Amortization	$ 110,608	$ 104,764
Intangible Assets, Gross (Excluding Goodwill)	281,875	281,106
Intangible Assets, Net (Excluding Goodwill)	171,267	176,342
Tradenames
Acquired Intangible Assets
Indefinite-Lived Intangible Assets	7,600	7,600
Purchased research and development
Acquired Intangible Assets
Indefinite-Lived Intangible Assets	4,687	4,687
Customer Relationships
Acquired Intangible Assets
Finite-Lived Intangible Assets, Gross	192,853	191,919
Accumulated Amortization	58,682	54,889
Net Balance	$ 134,171	$ 137,030
Customer Relationships | Minimum
Acquired Intangible Assets
Estimated Useful Life in Years	6 years	6 years
Customer Relationships | Maximum
Acquired Intangible Assets
Estimated Useful Life in Years	16 years	16 years
Patents
Acquired Intangible Assets
Finite-Lived Intangible Assets, Gross	$ 58,730	$ 58,787
Accumulated Amortization	41,350	40,079
Net Balance	$ 17,380	$ 18,708
Patents | Minimum
Acquired Intangible Assets
Estimated Useful Life in Years	3 years	3 years
Patents | Maximum
Acquired Intangible Assets
Estimated Useful Life in Years	19 years	19 years
Tradenames
Acquired Intangible Assets
Finite-Lived Intangible Assets, Gross	$ 10,832	$ 10,885
Accumulated Amortization	5,847	5,507
Net Balance	$ 4,985	$ 5,378
Tradenames | Minimum
Acquired Intangible Assets
Estimated Useful Life in Years	3 years	3 years
Tradenames | Maximum
Acquired Intangible Assets
Estimated Useful Life in Years	15 years	15 years
Non-compete Agreements
Acquired Intangible Assets
Finite-Lived Intangible Assets, Gross	$ 6,864	$ 6,919
Accumulated Amortization	4,580	4,148
Net Balance	$ 2,284	$ 2,771
Non-compete Agreements | Minimum
Acquired Intangible Assets
Estimated Useful Life in Years	3 years	3 years
Non-compete Agreements | Maximum
Acquired Intangible Assets
Estimated Useful Life in Years	6 years	6 years
Other
Acquired Intangible Assets
Finite-Lived Intangible Assets, Gross	$ 309	$ 309
Accumulated Amortization	149	141
Net Balance	$ 160	$ 168
Other | Minimum
Acquired Intangible Assets
Estimated Useful Life in Years	2 years	2 years
Other | Maximum
Acquired Intangible Assets
Estimated Useful Life in Years	12 years	12 years